Conventional olive pitting machines employ a camdriven pitting knife and a coaxially mounted, opposed, cam-driven coring knife to remove a pit from an olive. Typically, the pitting knife has a cross-shaped profile (such as the profile of knife 72 or 74 in FIG. 6), and the coring knife has a circular profile (such as the profile of knife 22 or 24 in FIG. 2). Each olive is held during the pitting operation in a position so that the olives's longitudinal axis coincides with the axis of the opposed pitting and coring knives. The coring and pitting knives simultaneously penetrate opposite ends of the olive. Then, the coring knife retracts, and the pitting knife pushes the pit out from within the olive through the cylindrical passage produced by the coring knife.
One problem with this type of conventional pitting machine is that, as the pitting knife pushes the pit toward the retracting coring knife, the olive portion clinging to the pit often tears away at the pitting knife entry point. This "tear-out" phenomenon occurs especially frequently when olives of the "cling-stone" variety are being pitted. The tear-out phenomenon detracts from the appearance of the torn pitted olives, and reduces their value.
When cling-free olives (which do not frequently tear at the pitting knife entry point) are processed with the conventional pitting machine described above, another disadvantage of such conventional machine is that the coring knife removes a substantial portion of the olive flesh. Thus, the pitted olives produced by this type of machine have a lower average weight than they would have if the coring knife would remove less flesh from the olive.
It has not been known until the present invention how to eliminate both the "tear out" problem and the reduced yield problem, which are inherent in operation of conventional olive pitting machines.